Related papers: The Extragalactic Diffuse Gamma-Ray Emission
The public data from the EGRET space telescope on diffuse Galactic gamma rays in the energy range from 0.1 to 10 GeV are reanalyzed with the purpose of searching for signals of Dark Matter annihilation (DMA). The analysis confirms the…
Several high-frequency peaked BL Lac objects such as Mrk 501 are strong TeV emitters. However, a significant fraction of the TeV gamma rays emitted are likely to be absorbed in interactions with the diffuse IR background, yielding…
More than 90% of the Galactic gas-related gamma-ray emissivity above 1 GeV is attributed to the decay of neutral pions formed in collisions between cosmic rays and interstellar matter, with lepton-induced processes becoming increasingly…
The LHAASO Collaboration has recently reported a measurement of the diffuse gamma-ray emission from the Galactic Plane at energies between 10 TeV and 1 PeV. While this emission is brighter than that expected from cosmic-ray interactions in…
Here we investigate to what extent unresolved \gr pulsars contribute to the galactic diffuse emission, and further whether unresolved \gr pulsars can be made responsible for the excess of diffuse galactic emission above 1 GeV which has been…
The majority of galactic gamma rays are produced by interaction of cosmic rays with matter or radiation fields. This results in a diffuse radiation concentrated in the galactic plane where the flux of cosmic rays and the density of material…
Ultra-high energy cosmic rays interacting with the radiation fields in the universe cause electromagnetic cascades resulting in a flux of extragalactic gamma rays, detectable to some 100 GeV. Recent precise measurements of the extragalactic…
The emission mechanism of the gamma-ray bursts (GRBs) is still a matter of debates. The standard synchrotron energy spectrum of cooling electrons F_E ~ E^{-1/2} is much too soft to account for the majority of the observed spectral slopes.…
We show that the current extragalactic gamma-ray background (EGB) measurement below 100 GeV sets an upper limit on EGB itself at very high energy (VHE) above 100 GeV. The limit is conservative for the electromagnetic cascade emission from…
Structure formation in the intergalactic medium (IGM) produces large-scale, collisionless shock waves, where electrons can accelerate to highly relativistic energies. Such electrons can Compton scatter cosmic microwave background photons up…
Observations of very-high-energy (VHE, E > 250 GeV) gamma-ray emission from several blazars at z > 0.1 have placed stringent constraints on the elusive spectrum and intensity of the intergalactic infrared background radiation (IIBR).…
Astrophysical sources outside the Milky Way, such as active galactic nuclei and star-forming galaxies, leave their imprint on the gamma-ray sky as nearly isotropic emission referred to as the Extragalactic Gamma-Ray Background (EGB). While…
Using the HEGRA system of imaging atmospheric Cherenkov telescopes, a region of the Galactic plane (-10 deg < b < 5 deg, 38 deg < l < 43 deg) was surveyed for TeV gamma-ray emission, both from point sources and of diffuse nature. The region…
The origin and nature of ultrahigh energy cosmic rays with energies above $10^{20}\,$eV is a puzzle for the physics and astrophysics of cosmic rays which is still unresolved. In this paper, I report on an extensive study on the propagation…
Very recently, the Tibet-AS$\gamma$ collaboration reported the detection of $\gamma$ rays from the galactic disk in the energy range of 100 TeV -- 1 PeV. Remarkably, many of these $\gamma$ rays were observed apart from known very high…
Galactic diffuse gamma-ray emission is produced by the interaction of high-energy cosmic rays propagating through the Milky Way with interstellar gas and radiation fields. Its measurement can provide crucial insights into the acceleration…
We obtained new upper limits on the diffuse gamma rays from the inner Galactic (IG) and outer Galactic (OG) planes in 3.10 TeV region, using the Tibet air shower data and new Monte Carlo simulation results. A difference of the effective…
The Compton Gamma-Ray Observatory (CGRO) experiments EGRET and COMPTEL observed the Virgo sky region continuously for 7 weeks between December 10, 1996 and January 28, 1997. The prominent quasar 3C~273 was found to be the brightest source…
The diffuse galactic EGRET gamma ray data show a clear excess for energies above 1 GeV in comparison with the expectations from conventional galactic models. The excess is seen with the same spectrum in all sky directions, as expected for…
The Fermi-LAT telescope has measured the extragalactic gamma-ray background (EGB) generated by the ensemble of all extragalactic sources. The energy distribution of the EGB is well described as a power-law with a spectral index…